1. Cadillac CT5/CT4 O2 sensor

Original Equipment Part Number (OE NO):
CT5 upstream(Front) Oxygen Sensor part No.: 12658134 (2.0T LSY engine)
CT4 Downstream(Rear) Oxygen Sensor part No.: 12658135 (1.5T/2.0T common)
Defender Oxygen Sensor Fault Codes & Symptom Signs
P1098: Fuel Pressure & Oxygen Sensor Signal Contradiction (High Pressure Fuel Pump Failure or Sensor Poisoning)
P0171/P0172：Mixture too thin/thick (poor fuel quality or dirty MAF sensor)
What causes & How to repair
Sensor signal drifting due to high turbo temperature after track driving; Sulfide poisoning accelerated by ethanol gasoline use.
How much oxygen sensor cost to replace?
OEM sensor: 300-500 (150-200 labor cost)
OEM parts (e.g. Bosch): 150-300

2.Cadillac SRX/XT5 O2 sensor

OE part number (OE NO):
SRX upstream(Front) Oxygen Sensor part No.: 12658136 (3.6L V6 engine)
XT5 Downstream(Rear) Oxygen Sensor part No.: 12658137 (common with GMC Acadia)
Defender Oxygen Sensor Fault Codes & Symptom Signs
P0420: Catalytic converter inefficiency (three-way catalytic converter failure or rear oxygen sensor deterioration)
P2270: Rear Oxygen Sensor Signal Sticky (Heating Circuit Failure or Fuel Sulfur Contamination)
What causes & How to repair
Overheating of the sensor due to high engine load when towing a motorhome; delayed heating due to low temperatures in cold areas.
How much oxygen sensor cost to replace?
OEM sensor: 350-600 (labor 200-300)

3.Cadillac Escalade O2 sensor

OE part number (OE NO):
6.2L V8 upstream(Front) Oxygen Sensor part No.: 12768903
Diesel Downstream(Rear) Oxygen Sensor part No.: 12768904
Defender Oxygen Sensor Fault Codes & Symptom Signs
P2297: Abnormal Oxygen Concentration during Diesel Deceleration (Fuel Sulfur Contamination or DPF System Malfunction)
P0030: Heating Circuit Fault (Harness Short or ECU Power Abnormal)
What causes & How to repair
Mud and water erosion sensor interface in off-road scenarios; abnormal linkage of urea injection system in diesel models
How much oxygen sensor cost to replace?
OEM sensor: 500-900 (labor cost 300-500)

4.Cadillac CTS/ATS O2 sensor

Original Equipment Part Number (OE NO):
CTS 2.0T upstream(Front) Oxygen Sensor part No.: 12658132(LTG engine)
ATS Downstream(Rear) Oxygen Sensor part No.: 12658133 (common with CT4)
Defender Oxygen Sensor Fault Codes & Symptom Signs
P0134: No Signal (Plug Oxidized or Circuit Disconnected)
P2096: Rear Oxygen Signal Too Dilute (Exhaust System Leak or Clogged Injector)
What causes & How to repair
Sensor signal interference due to exhaust modification; Carbon buildup after aggressive driving
How much oxygen sensor cost to replace?
Genuine sensor: 250-400 (labor cost 100-180)
Cadillac General Repair Recommendations
Diagnostic Prioritization:
Test wiring harness and plugs first (40% of failures), then clean or replace sensors
Use Tech2 or GDS2 diagnostic tools to calibrate signals (Escalade in particular requires special programming)
Parts selection strategy:
Genuine parts fit best (VIN compatibility verified through GM SPO system)
Cost-optimized solution:
Purchase the sensor yourself and then commission a third party to repair it, saving 30%-50% on labor costs.
Data Sources and Expansion Recommendations
The above information is synthesized from Cadillac Technical Bulletin (TSB 21-NA-013), GM Repair Manuals and RepairPal cost statistics. Real-time parts price fluctuation is recommended to check through GM Parts Now or local dealers. In-depth trouble code analysis can be found in the Cadillac TIS Technical Document (subscription required).

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